SAP Mix

FW: Ontape remote tape backup performance ...

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Date:

Hi,

I checked the network data transmit rate for a FTP transfer. It sends data
of 215 MB/hour approximately. Our level 1 backup size for this box is
around 1.5 GB.Whatever network delay happens, it should have completed by 10
hrs at the max. But it takes 45 hrs to complete just the level-1 backups.

Just to recollect, We have done the same remote tape backups when this box
was in the same building and the level-1 took only 2 hrs. Considering our
network throughput, I expect the backup delay but not to the extent of 45
hrs. Since Level-1 spends most of the time doing disk reads within the box
when compared to data transfer thru the network, i am wondering why it takes
so much time on reading.

I would like to clarify the following doubts.

1) Do we have to fine-tune OS kernel parameters for remote tape backups like
more buffers etc.?
2) I could see the "onstat -g ioq" maxlen shows upto 70 during the backup
run. I guess its normal during the backups.
3) I would like to fine-tune OS/database if the backup delay caused within
the box. Please pass on your suggestions.
4) Apart during data transfer during level-1, Does ontape communicates with
the network for some reason even while performing disk reads which
cause the delay ?

Thanks

Rajesh Rajasekaran
Informix Database Administrator
Forest Pharmaceuticals Inc.
314-493-7073 (Work)
314-662-6619 (Cell)
314-514-2457 (Home)


-----Original Message-----
From: Rajasekaran, Rajesh
Sent: Thursday, January 30, 2003 2:56 PM
To: 'Julio Porras'
Subject: RE: Ontape remote tape backup performance ... [32]


Hi,

I did test ftp on to SBX from DEV before. Although its not 1gb, i could
transfer files say 10 mb in < 5 mins time.

Rajesh Rajasekaran
Informix Database Administrator
Forest Pharmaceuticals Inc.
314-493-7073 (Work)
314-662-6619 (Cell)
314-514-2457 (Home)


-----Original Message-----
From: Julio Porras [mailto:Julio.Porras@venalum.com.ve]
Sent: Thursday, January 30, 2003 2:15 PM
To: 'Rajasekaran....'
Subject: RE: Ontape remote tape backup performance ... [32]


Try an ftp transfer from DEV to SBX. Use a LARGE file (1GB+) and measure the
bandwidth available between the two servers.- This might help you trace out
the cause of your problem by eliminating a network bandwidth shortage.

Hope this would be of some help.

Julio Porras
Especialista de Sistemas
CVG Venalum
286-9506898
416-7985875

-----Original Message-----
From: Rajasekaran.... [mailto:RRajasekaran@forestpharm.com]
Sent: Jueves, 30 de Enero de 2003 11:27 a.m.
To: sapmix@iiug.org
Subject: Ontape remote tape backup performance ... [32]

Hi,

I would like to clarify a performance issue regarding the ontape remote
backups. We are running SAP R/3 in our site.We have two servers namely
DEV,SBX. The DEV box has got a DLT 7000 tape drive attached to it. DEV
system is configured to permit remote access to its tape drive for SBX to
perform its backups. I'm using "ontape" tool for Level 0/1 database backups
on these systems.

Till recently, we had both systems were on the same network (same
building). Though the tape drive is connected to DEV, our SBX level 1
backups completes inside 2.5 hrs. Now we moved our SBX system to a remote
site (different network,different office from DEV).

Since moving, i performed my first Level 1 backups. Its running almost for 2
days and still not completed. I could make out the Level 1 backups still
running and completed few dbspaces from the "onstat -g arc" command.

NOTE: Our Network infrastructure currently at remote site is not on par with
our main site and its way ahead in terms of speed,data transfer etc.

My point is
1) In an incremental backup(Level 1) on a not-so-heavily modified database
since last level-0 , database will spend more time on reading all the pages
for changes if any since last level 0. What are the chances of slow down on
reads of database pages so heavily in a remote site scenario ?

2) Most of the time,"onstat -u" reports "Y-AP--M" for the primary backup
thread. This means, it waits for some response from ontape to continue say
further scans on pages . Does ontape wait for any response from tape drive
? This could cause delay if has to come over the network quite frequently.

3) I know Network bottleneck cause some slow down in this case. Also, i
feel there could be a slow down within the box for a level 1 backups due to
some reasons.

Any comments/suggestions on other areas to monitor is greatly appreciated.

Thanks
Rajesh Rajasekaran
Informix Database Administrator
Forest Pharmaceuticals Inc.
314-493-7073 (Work)
314-662-6619 (Cell)
314-514-2457 (Home)

Messages In This Thread

• FW: Ontape remote tape backup performance ...
  -- Tuesday, 4 February 2003, at 10:43 a.m.

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